Metal sealant containing oxyalkyl amine accelerator



United States Patent Office 3,544,536 Patented Dec. 1, 1970 3,544,536 METAL SEALANT CONTAINING OXYALKYL AMINE ACCELERATOR Charanjit Rai, Bellwood, and Arthur Frederic Krueger,

Villa Park, Ill., assignors to Broadview Chemical Corporation, a corporation of Illinois No Drawing. Filed June 20, 1966, Ser. No. 558,595 Int. Cl. C08f 3/62, 15/16, 7/12 U.S. Cl. 260-895 9 Claims ABSTRACT OF THE DISCLOSURE For accelerating a shelf stable room temperature setting sealant composition while retaining shelf stability, accelerators are proposed having the formula wherein m and n are each integers 1 to 2 inclusive, the total of m and n is 3, x is an integer 1 to .6 inclusive, y is an integer to 6 inclusive, R is a lower alkyl chain and R is selected from the class consisting of hydrogen and lower alkyl groups.

This invention relates to accelerating the cure of room temperature sealants containing liquid monomercatalyst mixtures which are shelf stable but capable of setting up at room temperature on confinement between closely facing metal surfaces to adhere the surfaces to each other.

Briefly, the present invention involves the use of certain oxyalkyl amine compounds as accelerators for shelf stable sealant compositions containing a room temperature reactive monomer and a catalyst system for initiating polymerization of the monomer at room temperature.

Shelf stable metal sealant compositions have been formulated for the purpose of bonding closely facing metal surfaces, e.g., threaded joints, in a full range of varying strengths, viscosity, thixotropy and curing or setting rates. Such sealant compositions usually include a room temperature reactive acrylic monomer which is capable of being cured at room temperature within the desired period of time. For example, the acrylic monomer may be an acrylic diester of an ethylene glycol, e.g., a polyethylene glycol as described by L. W. Kalinowski in U.S. Patent No. 3,249,656, entitled Sealant Composition, patented May 3, 1966; an acrylic ester of a cyclic ether alcohol as described by J. R. Stapleton in application Serial No. 517,321, entitled Adhesive Composition for Metals and the Like, filed Dec. 29, 1965, now abandoned; an acrylic ester of an amino alcohol such as described in my copending application Serial No. 561,381, entitled Metal Sealant Containing Amino Acrylic, filed June 29, 1966, now abandoned, and/or mixtures of the above with each other or with other vinylic monomers such as allylic monomers. The disclosures of monomers and the specific examples of such monomers described in the above-identified patent applications are hereby incorporated in this application by reference as examples of sealant compositions which are useful in the practice of the present invention as set out herein. The room temperature reactive monomers are used in an amount sufiicient to complete the desired room temperature curing reaction when the catalyzed sealant is confined between the closely facing metal surfaces.

The catalysts for sealant compositions with which the present invention is concerned are usually peroxidic catalysts. Although t-butyl hydroperoxide is a common and conventional peroxidic initiator for ethylenic polymerization generally, it is difficult to initiate polymerization of composition using t-butyl hydroperoxide and it is also diflicult to provide high strength grades while still maintaining shelf stability.

It is a general object of this invention to provide new and useful adhesive compositions of the class described; and it is a more particular object to provide a new and useful accelerator system for such adhesives or sealants.

It is another object of this invention to provide new and useful liquid sealant compositions which will set up at room temperature in contact with closely facing metal surfaces within a reasonable time to provide a bond having excellent strength.

Still another object of this invention is to provide a high strength sealant composition which has good stability and an acceptable rate of room temperature cure.

A further object of this invention is to provide a new and useful sealant composition employing a highly advantageous accelerator system.

Other objects of this invention will be apparent from the descriptions given herein.

The useful oxyalkyl amines have the formula wherein m and n are each 1 or 2, m.- plus n equals 3, x is an integer 1 to 6 inclusive, y is an integer O to 6 inclusive, R represents a lower alkyl chain, e.g., of 1 to 6 carbon atoms inclusive, and R is hydrogen or lower alkyl, e.g., C to C alkyl. Specific examples of suitable oxyalkyl amines are diglycol amine, di-(triethylene glycol) amine and other di-(polyethylene glycol) amines including di-(hexaethylene glycol) amine, methoxypropyl amine, hydroxypropyl amine, methoxymethyl amine, hexyloxyhexyl amine, 2-etl1oxy-3, 4-dimethyl hexyl amine, ethoxy ethoxyethoxyethoxyethoxyethoxyethyl amine, butoxybutoxy amine, ethoxyethoxyhexyl amine, hydroxyhexyloxyhexyloxy butyl amine, di-(hydroxybutoxybutoxy butyl) amine, di-(methoxypropyl) amine, etc.

To prepare the present sealant compositions, it is merely necessary to mix a suitable amount of the oxyalkyl amine compound and peroxide catalyst with the selected reactive monomer or mixture of monomers. Metal containers should not be used because of the chance of premature polymerization. It has been found that the peroxide catalyst, e.g., organic peroxide, including hydroperoxides and peresters, or hydrogen peroxide can be used, e.g., in amounts of .1 to 10 or 15% or more, preferably 1 to 8%, and usually 1 to 3% in the sealant composition. The amount of accelerator may vary from'.01 to 10 or more weight percent and an optimum can usually be found between .1 and 5 weight percent depending on the monomer system and peroxide catalyst used. The preferred amount of accelerator is .5 to 2%.

Examples of suitable organic peroxides are cumene hydroperoxide, t-butyl hydroperoxide, methylethylketone tetralin hydroperoxide, ditertiary butyl diperphthalate, and the like. Tertiary butyl hydroperoxide sealants base batches have been given code numbers as can be advantageously used. follows:

Inhibitors or stabilizers can be added as need to balance or prevent instability of the sealant. Hydroquinone and its Composition ethers, such as p-methoxy phenol are preferred inhibitors Code and stabilizers because of their availability and etfectivea Number; ness to inhibit until it is desired to set up sealant com- 0122"" g gfggfgmfi position between the closely facing metal surfaces in the absence of air. Hydroquinone, or an ether thereof, in a Methxyprpylaminetotal amount f 25 to 1000 p.p.m., more usually 50 to 0204-"- Ethoxyethoxyethoxypropylamine. 400 p.p.m., wil l probably be sufficient to stabilize most 0206" Ethoxyethoxypmpylamim sealant compositions containing the ester. Other conventional inhibitors or stabilizers for inhibiting polymeriza- (2) Monomers tion of vinyl compounds can be used as will be apparent 0133-.-- Mixed monoand di-methacrylates of 2,2,4-trimethylto those in the art. Pentanediol' It is intended that other polymerizable unsaturated Tetfahydmmrfurylmethacl'ylate' esters or other unsaturated monomers such 38 hydrocar- 210 Polyethylene glycol dimethaerylate (averages tetraethylene bons, ethers, or other comonomers, or plasticizers such glycoldimethacfylate as diisodecyl phthalate or the monobutyl ether of ethylene 1212"" Dimethylaminoethyl methacrylate. glycol, can be included in the present sealant composi- (3) cocatalysts tions to modify the properties of the composition.

Preferred sealant compositions also include a minor amount, e.g., up to 50% of a low molecular weight poly- 0325--.- N,N-diallylformamide. mer of an allyl ester of an aromatic polycarboxylic acid 0332--.- s d. hereinafter referred to as allylic prepolymer, which 18 20 ucclmml a soluble in and copolymerizable with the reactive acrylic 0115. N,N-din1ethyl formamide.

(4) Sealant base batches monomer. These compositions may be conveniently pre- 1000. n bete n meoe b rtllixgnog 2o pmngs of ethyleg ne glygioo ime acry D. 6 V1 poun S 0 a premix erea er pared by PremmPg the acryhc monomer and PIC identified as Premix) containing 73.7% 210 (identified polymer to provide a generally homogeneous mixture abovel) and 26.3%J gligllylghtlollate prepogymer 5a)solig prepo ymer mar e 6 un 81 e name apon- 111 preferably pnor to addmqn of catalyst and inhibitedwith 100p.p.m. hydroquinone, and then adding An allylic prepolymer having desirable characteristics as and mixing in 132 g. (about 1%) acrylic acid and 60 g.

diallyl phthalate which can be obtained under the name (abmt 03%) sulfimme' Dapon from Food Machinery Corporation, having ATB-l-.... A batch made by adding 650 g. of silica, 4 pounds of diisodec 1 hthalate and 4 ounds of but 1 carbitol to 20 the following reported physical properties. pouadgofpremm p y 35 B lk d it 14 16 lb f ATE-2..- A3l6atch nilatzlooby adding 4.3 pounds of butyl carbitol to mm s Sp'gr'at25c-L267 AT Abin d b dd 4 d fd d 1 hthlt B3 ac ma e ya ing poun so iiso ecy p aa a Iodme 57 to 30 pounds of Premix.

Softening range-85415 C.

ATB-4 A gatch Folde by adding (it pounds of butyl carbitol and The compositions of this invention are useful in ad- 7 S m to 30 Donn so Premlx' ATB5 A batch made by adding 100 g. of diisodeeyl phtlialate hering closely facing surfaces, usually metal, to each and 725 g of sum to 30 pounds Premix other. Close contact of the sealant composition with the TABLE OF EXAMPLES Example No.

Ingredients 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 (1) Accelerators, percent:

1 Reported as parts by weight.

metal surfaces apparently results in initiating the cure The formulations of Examples 1 through 13 were sub- Of the monomer y the catalyst and acceleratofjected to a finger-tight locking test. Accordingly, 3 small The following examples are f? the R P of drops of each formulation were dispensed on the exposed illustration and are not intended as limiting the invention: threads of a plurality of separate degreased 3/844, 1 A L S 1 o 22 inch medium carbon steel cap screws on each of which a degreased medium carbon steel nut had been threaded In each of these examples, the ingre 1n the up close to the cap screw head. The nut was then backed amounts indicated in the table below werethoroughly mixed, with the accelerator, cocatalyst (where used) and off 1mm It was wlthm the area of threads to whlch the about 2.5% t-butyl hydroperoxide as catalyst being added formulation had been aPPHed- The cap Screw was then and mixed seriatim as the last ingredients, unless other. placed head down on a level surface and allowed to stand. wise indicated. For ease of reporting the formulations and Every 30 minutes a different cap screw for each formularesults, various accelerators, monomers, cocatalysts and tion was checked until one was found to be finger tight,

i.e., the nut could not be manually turned relative to the cap screw without the aid of a wrench or other tool.

Accelerated shelf life tests were also conducted on samples of Examples 1-15 in order to determine the storage stability of representative compositions. In accordance with the test procedure, each composition, in its polyethylene bottle, was aged in an oven maintained at about 81 to 82 C. If the composition gelled, the time was noted. The test is an accelerated aging test and, as a correlation of the test procedure with actual storage conditions, a sealant composition free from gelling after 30 minutes under the aging conditions of the test will also be free from gelling under ambient or room temperature for at least one year. None of the samples gelled within 30 minutes and many showed stability after extended periods of time.

Additional cap screws were prepared as above for some of the examples for the purpose of testing the strength of the bonds between the nuts and cap screws after 24 hours and in some cases at 90 minutes and 6 hours. After expiration of the time intervals given below in Table I, the head of the appropriate cap screw was held in a vise with the shank of the cap screw disposed vertically. A torque wrench was applied to the nut, and the torque required to dislodge the nut was noted. The results are an average of three to five tests. The results of the finger tight, 24 hour torque and stability tests for Examples 1-13 were as follows:

TEST RESULTS invention encompasses, but are not limited to, the use of all accelerators listed herein above, since each is effective.

As additional examples of suitable formulations, the above examples are repeated except that the monomer is replaced with polyethylene glycol diaerylate, tetrahydrofurfuryl chloracrylate, dimethylaminoethyl methacrylate, butylaminoethyl methacrylate, or other room temperature curing acrylic monomers or mixtures of such monomers. The oxyalkylamine compounds have an accelerating effect on each such sealant formulation.

The sealant compositions of this invention can be used to bond similar or dissimilar metal surfaces. The surfaces are usually ferrous metal surfaces, although the compositions are useful in bonding such other metals as brass, copper and tin. Zinc and cadmium, used as corrosion resistant coatings on other metals, are less active metals and may require the use of a primer to activate the metal before applying the sealant. Suitable such primers are available commercially.

Many advantages of the present sealant composition have been discussed above; briefly, there is provided a sealant composition which is shelf stable for a extended period of time but which sets up when closely contacted or confined between metal surfaces. The sealant compositions are receptive of and compatible with a variety of addition agents, including a full range of plasticizers, e.g., esters of phthalic acid, waxy plasticizers, etc., thixotroping agents such as a silica gel, e.g., Cab-O-Sil, and a variety of other monomers and soluble polymers.

t 30 It has previously been proposed by V. K. Krieble in iiilf Torque Stability US. Patent No. 3,041,322 to use triorganoamin es as i t 241101118, accelerators for t-butyl hydroperoxide polymerization of mm certain diand tri-esters of acrylic acid and specific alkyl- 128 90 ene and polyalkylene glycols and glycerols, defined by a 20 150 90 structural formula in that patent, in shelf stable sealant 20 174 90 compositions. This patent requires that the amine be one 100 112 90 100 60 90 in which all three valences of the nitrogen atom are satisg8 32 :28 fied by carbon atoms, and that there be no hydrogen on 1 3 90 the amine nitrogen. The present accelerators are in direct g8 2 3% controversion of the above requirements since they are 71 amines which can have hydrogen on the amine nitrogen 60 and are not triorganoamines and they still operate suc- 40 so 90 cessfully as shelf stable compositions. 1 Geued at 90 minut9s- All percentages given herein are percentages by weight Examples 14 to 22 were also tested for finger tight unless otherwise indicated. time and 24 hour torque substituting cadmium plated bolts The foregoing detailed description is given for clearand nuts for the steel ones. These examples were further ness of understanding only and no unnecessary limitatested for stability by an extended aging test at F. tions are to be understood therefrom, as some modificafor 10 days and examined for gelling. Results are reported r0 tions will be obvious to those skilled in the art. Advanbelow. tageously, the accelerator system provided by the present TEST RESULTS Time to finger Torque, 24 Stability tight, n1in. hours, in./lb.

Viscosity, Cad- Cad- 82 0.1 10 days c.p.s. Steel mium Steel rnium min. at 120 13.

Example:

14 100, 000+ 30 9 90 No gelling 400, 000+ so 60 21 23 90 Do. 12 110 30 56 61 30 Do. 142 60 so 71 69 60 Do. 20 55 79 83 2 60 D0. 100, 000+ 30 60 11s 88 90 Do. 28,000 20 40 159 85 90 D0. 400, 000+ 50 40 66 68 90 Do. 400, 000+ 60 60 70 65 90 DO.

1 Gelled at 60 minutes.

2 Gelled at 90 minutes.

The temperature conditions during the preparation and invention is compatible with and useful in combination testing of all sealant compositions hereinabove were in with t-butyl hydroperoxide, as well as other peroxidic the range of about 70 F. to 75 F. catalysts, for accelerating room temperature cure without Although the oxyalkylamine compounds used in the materially adversely affecting room temperature storage above examples are preferred because of their commercial 70 life of the mixed monomer hydroperoxide and acceleraavailability or case of manufacture, as further specific examples of formulations of this invention other similar oxyalkylamine compounds as described generally above can be substituted for acceleration in any of the examples tor.

We claim:

1. A shelf stable liquid sealant composition which is shelf stable under room temperature storage conditions with similar results. Thus, the working examples of the 75 and nonsetting at about 81 to 82 C. for at least 30 minutes in isolation from contact with metal surfaces and comprising a room temperature reactive liquid acrylic ester monomer selected from the class consisting of diesters of an acrylic acid and a polyhydric alcohol, acrylic esters of cyclic ether alcohols, acrylic esters of amino alcohols, and mixtures thereof, a peroxidic initiator in an amount sufficient to initiate polymerization of said monorner at room temperature and an oxyalkylamine compound having the formula (H) N((CH (OR OR wherein m and n are each integers 1 to 2 inclusive, the total of m and n is 3, x is an interger 1 to 6 inclusive, y is an integer 0 to 6 inclusive, R is a lower alkyl chain and R is a lower alkyl group, in an amount sufficient to accelerate the polymerization of said monomer at room temperature on confinement of said sealant between closely facing metal surfaces without adversely affecting storage stability.

2. The composition of claim 1 wherein said oxyalkylamine compound is selected from the class consisting of diglycolamine, methoxypropylamine, ethoxyethoxypropyl amine and ethoxyethoxyethoxypropyl amine.

3. The composition of claim 1 wherein said oxyalkylamine compound is present in an amount of from .1 to 5 weight percent based on said monomer.

4. The composition of claim 1 wherein said peroxidic initiator is an organic hydroperoxide.

5. The composition of claim 1 wherein said peroxide initiator is t-butyl hydroperoxide.

6. A laminate structure comprising separate members having closely facing ferrous metal surfaces and. a layer of the composition of claim 1 set between said surfaces and securing said members as a unit.

7. A laminate structure comprising separate members having closely facing ferrous metal surfaces and a layer of the composition of claim 2 set between said surfaces and securing said members as a unit.

8. A method of adhering closely facing metal surfaces, which method comprises interposing between said surfaces the liquid composition of claim 1 and permitting said surfaces to stand at ambient conditions until said composition is set.

9. A method of adhering closely facing metal surfaces, which method comprises interposing between said surfaces the liquid composition of claim 2 and permitting said surfaces to stand at ambient conditions until said composition is set.

References Cited UNITED STATES PATENTS 2,268,611 1/1942 Mitchell 260-861 2,464,826 1/1949 Neher et al. 260-861 2,485,270 10/1949 Folt 260-86.1E 3,041,322 6/1962 Krieble 260-895 3,203,941 8/1965 Krieble 260-86.1 3,249,656 5/1966 Kalinowski 260-885 3,331,810 7/1967 Lee 260-861 3,331,812 7/1967 Lee 260-861 HARRY WONG, 111., Primary Examiner US. Cl. X.R. 

